Raxjio  receiving circuit



' T. H. BERKLAND April RADIO RECEiVING GIRCUIT Re Filed July 15. 1925 Original Filed July 13, 1925 llllllllllllllmw VET-' 1: I?

' Jlz'ozzga; J/jedrdand Reiuued Apr. 28, 1931 UNITED STATES PATENT OFFICE THOMAS BER KLAND, OI CHICAGO, ILLINOIS, A SSIGNOR TO WESTERN ELECTRIC COM- PANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK:

RADIO RECEIVING CIRCUIT original in. 1,679,597, dated August 7, 1925; serial No. 43,115; filed July 13, 1925. Application. for reissue ,This invention relates to radio circuits and has for its object the provision of a radio circuit for receiving sets which will provide a maximum of selectivity and-clearness' of l'cceptiql.

Other and further important objects of this invention will be apparent from the disclosures in the specification a-nd' the-accompanying drawings; I Thisginarntion '(in a preferred form) is illustrated .in the di-awings and hereinafter m'oreff'ully described On the drawings: The figure of the "diagrammatic slietch of a circuit embodying the principles of this invention.

As shown on the-drawings An antenna 1 is connected to the primary 2 of a", radio frequency transforinen having a variable condenser 3 in series with said primary and antenna. There is connected to the variable condenser 3 opposite to said primary 2 one terminal of a secondary coil 4 and the grid of a'-vacu1im tube5. Connectedto the other terminal .of-the secondary coil 4 is the negative side of a C-battery 6. A second vacuum tube 7 is also provided, 'the filaments of the vacuum tubes 7, and 5 being connected. in parallel through, their respectiveresistances across an A-battery 8.

A B-battery9'is,provided having sixtyseven voltsacross its extrefrie terminals 10 and 11 respectively. An intermediate ter;

minal '12 is provided on the "EB-battery 9 for providing a voltage of forty-five volts. second radio frequency transformer is pro-.

vided having a primary 13,1a' variable condenser 14 connected to one end of said pri- -mary and a secondary 15 having one end a connected to said variable condenser 14 opposite said primary. The other end of the secondary 15 is connected to the filaments of the vacuum tubes at the {positive side of the A-battery 8. The other 'end of the priinary 13 is connected to the positive side of .the .B-battery 9 at the terminal 10. The.

"grid of the vacuum tube T. is connected to' [the variable condenser 14 on the side oppo- -site to the primary 13 through a grid con- 0 denser and leak 16. The plate of the drawings represents a Serial No. 472,092.

-1-')ri nia'r 1;} thereof find the variable condenser l l. ll rc ji'iegative sides of the filainentsol the vacuum tubes Wand 5 are conncctcdtotho negative side of the A-battery S and also'tothe negative terminal11 of y the B-balterv 9. The negative terminal 11 of'tlie B-haitery 9. is also connectedjto the positive side of the C-battery 6.". vvThe plate of the vacuum tube .7 is connecteduto the intermediate forty-five volt terminal 12 of the B-battcry 9 through a pair of phones 17, or lilieinstrln'neirt, such as aloud speaker. The negative terminals of the A and.B.-ii-at- 'teries and the positive terminal 'of the Chat tery are connected to ground-at 18through suitable conductor 19 as shown.

It will be apparent that the above arrangement permits the-tui'iingof the input and output. circuitssimultaneously,- and that by balancing the. radio frequency and audio frequency circuits, as herein disclosed, a

maximum of selection and clearness of rece tionis obtained. I

am aware that many changes may be made, and numerous details ofconstruction may be varied through a Wide' range Without departing from the principlesofthis invention, and I therefore do not purpose limiting thepatent granted hereon, otherwise than necessitated by the prior art.

I claim as' my invention:

1. In a radio receiving system, a. ther- ,m ionic' tube, "the primary 'of' a radio frequency transformer, the secondary of said radio frequency transformer, said;'secondary conduetively connected at one end to the @grid of said tube and at the other end to a grid-potential -control battery, and the primary of said itrainsformer conductiyely connected to theantenna at one endand .capacitively. connected to the grid of said tube through a variable condenser at the other end.

2. In a radio receiving system, a thermitransformer, the secondary of said radio frequency transformer, said secondary conductively connected to the grid of said tube at 'onic tube, the .primary of a'radioifrequency one end and to the cathode at the other end, the primary of said transformer conductively connected to the positive ole of a plate. po-

- tential source at one end and capacitively connected to the grid of said tube through a variable condenser at the other end, and a conductive connection with the plate of another thermionic tube at the end of said primary at which it connects to the variable 0 condenser.

, 3. In a radio system, a thermionic tube, the primary of a radio frequency transformer, the secondary of said radio frequency transformer, said secondary conductively connected to the grid of said tube at one end and to the cathode at the other end, the primary of said transformer conductively connected to the positive pole of a plate potential-source at one end and ca-pacitively connected to the grid of said tube through a variable condenser at the other end, and a conductive connection with the plate of an; other thermionic tube at the end of said primary at which it connects to the variable condenser.

4. In combination, an electric space discharge device having an anode and a cathode, a second electric space discharge device having a cathode and a discharge control eleso ment, and a coupling circuit for coupling said anode and said control element, said circuit comprising a transformer having primary and secondary windings and a variable condenser for connection in series with said windings, said primary winding having a terminal connected to saidanode, said secondary winding having a terminal connected to said control element, and said condenser being connected between said terminals.

40 In witness whereof, I hereunto subscribe my name this 24th dav of July, 1930.

THOMAS H. BERKLAND. 

